NEGOTIATIONS are still on going, but the United Federation of Teachers has come close to settling for a 14 percent pay hike. The union’s thinking too small: Here’s how it could be 25 percent – with members’ jobs becoming more rewarding, to boot.

It’s not just possible: City teachers are already doing it – in charter schools.

As the UFT applies to open two charter schools of its own, perhaps now is a good time to look at what it is that has made these schools so successful and so appealing to teachers.

Charter-school teachers typically lack the tenure protections and collective-bargaining power of their unionized brethren – but they make up for it in greater job satisfaction, a more collaborative working environment and, yes, more pay.

For example, the Knowledge Is Power Program charter schools in the South Bronx and Harlem. KIPP co-founder David Levin notes that teachers at both schools make 20 percent to 25 percent more than their public-school counterparts – teachers with the same training and level of experience.

The “how” is no secret: They work more hours and more days. KIPP classes go from 7:25 a.m. to 5 p.m. on weekdays (and half-day most Saturdays), as opposed to the UFT’s six-hours-plus-change day. And KIPP’s school year is 220 days, as opposed to the UFT’s 180-day year.

Sound like a lot of work? If teachers want to get paid more, it’s far from unreasonable to expect them to work more. The UFT school day is now one of the shortest in the country.

The union says most teachers work far more hours than the contractual minimum. That’s probably true, but the unioninsistence on a lockstep pay scale and resistance to a longer official school day makes it impossible for teachers to be recognized or paid for that extra effort.

“If you work people really long hours, you want them to feel like they’re making what they should,” Levin says. “Our people generally feel well compensated.” Other charters have been able to give teachers merit pay and to pay bonuses in hard-to-recruit subjects like math and science.

And charter-school teachers typically also feel that their work is richly rewarded in the non-monetary sense.

When I visited the KIPP Academy in the South Bronx not long ago, teachers raved not about the pay, but about the supportive environment. Some, who had worked at public schools elsewhere, lamented the “clock-punching” culture in many union schools. At KIPP, everyone was expected to work hard and be on the same page.

I found the same thing last year at the Amistad Academy in New Haven, Conn. Sitting around a conference table (without their boss present), they gushed about how the charter environment – free from so many of the rules and regulations and labor-management tensions of the public schools they had taught at – gave them room to grow and thrive.

One teacher told the story of how the union rep at her old school used to tell her to make sure her car wasn’t in the school parking lot too late – it could set a bad precedent with management. At Amistad, her boss gave her the keys to the school.

And these aren’t isolated cases.

“Across the board, they’re happier campers,” says Michael Podgursky, an education economist at the University of Missouri, of charter-school teachers. “They’re more likely to say it’s a supportive environment . . . They’re more likely to say the principal understands what I’m doing.”

The flip side, however, is that charter-schools teachers (unsurprisingly, given their lack of access to endless grievance procedures) can and do get fired more often than unionized teachers.

And so this is the trade off.

Can New York City schools become less like factories – complete with an industrial-minded union – and more like schools?

The teachers would have to give up some job security and work longer hours. But they’d make more and kids would learn more.

For a union that talks endlessly of aspiring to “professionalism,” perhaps its time for the UFT to stop representing its members like assembly-line workers and start treating them like lawyers and doctors and entrepreneurs – people willing to take risks to reap rewards.

They can ask their pioneering colleagues who have taken the plunge into educational innovation: It’s worth it, in every sense of the word.